World’s Largest Cable Saddle Placed Atop Longest Self-Anchored Suspension Span
Steel Saddle Will Carry Bridge’s Nearly Mile Long Cable Over the Tower
view of the cable saddle taken April 15, 2011, as workers were readying
it at Pier 7 in Oakland. The cable saddle weighs approximately 450
tons, and while it has a rectangular flat base, two sides jut out.
The top is curved to better carry the cable over the top not just
once but twice, making it one of the few double cable saddles in
bridge construction and the largest and heaviest for a suspension
bridge. The base is 23.8 feet long and 19.7 feet wide. The saddle’s
length stretches to 32.8 feet close to the top. At the saddle’s
curved apex, it is 13.7 feet tall.
Update 4:45 p.m., May 19, 2011
The operation to lift the final structural piece into place started at 6 a.m. today, with the cable saddle expected to touch down between 7 and 8 p.m. Still to come is a decorative tower head.
Thursday, May 19, 2011
Strand jacks will hoist the 450-ton, steel cable saddle more than 500 feet into the air to place it onto a single steel component known as the "grillage" that was placed atop the four tower legs on April 15. This grillage will evenly distribute the weight of the cable saddle, and eventually the cable, amongst the four tower legs.
Cast in Japan (see story), the saddle will carry the SAS’ nearly mile-long single cable. Unlike traditional suspension bridges where the cables are anchored into the ground, a self-anchored suspension bridge’s cable is anchored in the road-decks. The cable will anchor into the east end of the roadway, travel up and over the tower to wrap around the west end before traveling back up and over the tower to anchor back into the east end.
According to Caltrans spokesman Bart Ney, "The 2.6-foot-wide cable will act like a giant, unbelievably strong sling."
The tower will be complete this summer when the tower head is placed. The new East Span is key element in a bridge seismic upgrade program overseen by the Toll Bridge Program Oversight Committee, made up of Caltrans, MTC's Bay Area Toll Authority and the California Transportation Commission.
For more information visit BayBridgeInfo.org/projects/sas-tower.
Metropolitan Transportation Commission • 101 Eighth Street, Oakland, California 94607
This page was last modified Thursday June 09, 2011
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